NAME¶

std::ranges::zip_view::size - std::ranges::zip_view::size

Synopsis¶

constexpr auto size() (1) (since C++23)
requires (ranges::sized_range<Views> && ...);
constexpr auto size() const (2) (since C++23)
requires (ranges::sized_range<const Views> && ...);

Returns the number of elements in the zip_view. Provided only if each underlying
(adapted) range satisfies sized_range.

Equivalent to:

return std::apply
(
[](auto... sizes)
{
using CT = /*make-unsigned-like-t*/<std::common_type_t<decltype(sizes)...>>;
return ranges::min({CT(sizes)...});
},
/*tuple-transform*/(ranges::size, views_)
);

Parameters¶

(none)

Return value¶

The number of elements, which is the minimum size among all sizes of adapted views.

Example¶

// Run this code

#include <algorithm>
#include <cassert>
#include <deque>
#include <forward_list>
#include <ranges>
#include <vector>

int main()
{
auto x = std::vector{1, 2, 3, 4, 5};
auto y = std::deque{'a', 'b', 'c'};
auto z = std::forward_list{1., 2.};

auto v1 = std::views::zip(x, y);
assert(v1.size() == std::min(x.size(), y.size()));
assert(v1.size() == 3);

[[maybe_unused]] auto v2 = std::views::zip(x, z);
// auto sz = v2.size(); // Error, v2 does not have size():
static_assert(not std::ranges::sized_range<decltype(z)>);
}

See also¶

ranges::size returns an integer equal to the size of a range
(C++20) (customization point object)
ranges::ssize returns a signed integer equal to the size of a range
(C++20) (customization point object)